The present invention relates to a welding machine for performing welding by shielding a weld part with a gas, and more particularly to a welding process which uses a consumable or non-consumable electrode in a specially designed torch head having a diameter smaller than conventional torch heads.
The welding torch can be used in a wide variety of welding processes, such as, but not limited to MIG, MAG, STT, and TIG welding. In a MIG, MAG or STT welding process, a consumable electrode wire is fed to a workpiece in which current is applied to the electrode to melt a consumable electrode and transfer the melted portion of the electrode to a workpiece. MIG, MAG and STT welding employs a continuously fed consumable electrode which is shielded by a shielding gas. An arc is formed between the workpiece and the consumable electrode which causes the electrode to melt and transfer to the workpiece in the form of a welding pool. The shielding gas typically employed is an inert gas which is supplied through the torch to protect the weld from oxidation and provide the desired arc characteristics during welding.
Several drawbacks exist with using existing welding apparatus for MIG, MAG and STT welding. During MIG, MAG and STT welding, a short circuit develops between the electrode and the workpiece during transfer of the molten metal to the workpiece. This short circuit occurrence typically results in spattering of the weld metal about the workpiece. This spatter can result in reduced quality weld beads and damage to the torch head or clogging of the torch head. In order to reduce the amount of spatter produced during the welding process, various control techniques have been devised. One such control technique for MIG welding to reduce spattering is the use of a pulse MIG process which is disclosed in U.S. Pat. No. 4,647,754, entitled xe2x80x9cConsumable Electrode-type Pulse Arc Welding Machine.xe2x80x9d A control technique to reduce spatter for STT welding is disclosed in U.S. Pat. No. 5,148,001, entitled xe2x80x9cSystem and Method of Short Circuit Arc Welding.xe2x80x9d U.S. Pat. Nos. 4,647,754 and 5,140,001 are incorporated herein by reference.
Another problem associated with MIG, MAG, STT, and TIG welding is that the torch head is too large for use in the welding of narrowly spaced areas. The torch head is generally a cylindrical design with a fresco-conical tip which has a cylindrical central passageway for the electrode, and one or more passageways formed about the electrode to accommodate shielding gases and/or cooling liquids. The incorporation of the passageways for the shielding gas and/or the cooling liquid results in a significantly increased diameter of the torch head.
Various torch head designs have been developed for use in narrower regions. Several of these torch head designs are shown in U.S. Pat. Nos. 3,992,603; 4,254,322; 5,900,167; and 5,981,897. In U.S. Pat. Nos. 3,992,603; 4,253,322 and 5,900,167, the torch head is formed as a linear torch head. In the ""603 patent, the torch head only includes an electrode opening and a cooling passageway positioned at one side of the electrode opening. The cooling passageway is linearly spaced from the electrode opening. The ""322 patent discloses a torch head design that includes an electrode opening, shielding gas passageways positioned on both sides of the electrode opening, and two cooling liquid passageways positioned on one side of the electrode opening. The shielding gas, cooling passageways and electrode opening are all linearly aligned with one another. The ""167 patent discloses a torch head that includes an electrode opening and two shielding gas tubes spaced from and positioned on both sides of the electrode opening.
Although these welding torch designs reduce one dimension of the torch head, i.e., the width, the length of the torch head is significantly increased. As a result, these torch heads can only be used in limited applications. Furthermore, due to the linear torch head design, the torch head is susceptible to bending when the torch head contacts the workpiece or other objects, thus resulting in improper welding and/or low quality weld bead formation. Furthermore, these torch head designs are highly susceptible to clogging due to spattering of the weld metal. Due to the narrow passageways of the tubes of these torch heads, spattering during the welding process can easily clog one or more of the tubes during the welding process. Furthermore, due to the design of the weld head, cleaning of the components of the weld head are very difficult, thus resulting in frequently replacing the components of the weld head. The linear design of these torch heads also does not provide uniform cooling of the torch head or uniform distribution of shielding gas about the electrode and weld metal. The proper cooling of the torch head facilitates in preventing damage to the components of the weld of the torch head. The proper distribution of shielding gas about the electrode and weld metal ensure proper arc characteristics during the welding process and facilitates in ensuring that a high quality weld bead is formed.
In view of the existing torch head designs, there is a need for a torch head design that has a smaller diameter than the present torch head designs and a torch head that provides adequate cooling to the torch head during welding and provides a uniformed and controlled distribution of shielding gas about the electrode and weld metal.
The present invention pertains to an improved welding torch head and more particularly to a welding torch head used in MIG, MAG or STT welding in which such welding torch head has a smaller torch head diameter than past torch heads to allow for welding in narrow workpiece regions. As can be appreciated, the invention has broader applications that can be used in other types of short circuit welding such as plasma arc welding, or TIG welding. However, the invention is particularly applicable to MIG, MAG and STT welding and will be described with particular relationship thereto.
In accordance with the principal aspect of the present invention, there is provided a welder that includes a torch head. In one embodiment, the welder includes a power supply to supply current to the electrode in the torch head. In another embodiment, the welder includes a welding circuit which controls one or more electrical or power parameters of the electrode during the welding process. In still another embodiment, one or more shielding gas sources are used with the welder to provide shielding gas about the electrode and/or to protect the weld metal during the welding process. Shielding gases also can be used to obtain the desired electric arc characteristics during a welding process. In still yet another embodiment, the welder includes a wire feeder to feed a consumable electrode through the torch head. In one specific aspect of this embodiment, the wire feeder includes a controller to feed the desired amount of electrode through the torch head during the welding process. The specially designed torch head of the present invention includes a base section and a body section connected to the base section. In a further embodiment, the base section includes one or more openings or connectors to enable one or more shielding gases and/or cooling fluids to be connected to the base section. When a consumable electrode is used, the base section also includes an opening to enable the consumable electrode to pass through the base section and into the body section of the torch head. In yet a further embodiment, the base section includes one or more electrical connectors to provide voltage and current to the electrode in the torch head. The body section of the torch head includes a uniquely designed arrangement of rods or tubes. These rods or tubes are arranged with respect to one another to form an inner chamber between the rods. In yet still a further embodiment, at least one of the rods includes an inner passageway to allow one or more shielding gases to pass there through. The passageway in the shielding gas rod allows shielding gas, which is directed into the base section of the torch head, to be conveyed through the base section and through the shielding gas rod. In still yet a further embodiment, the torch head includes at least two rods having inner passageways for the conveyance of cooling fluid within the inner passageways. These two cooling fluid rods enable cooling fluids, which is conveyed into the base section, to pass through the cooling fluid rods. The cooling fluid that passes through the rods cools the torch head components during welding. The rod design of the torch head provides an improved packaging arrangement for the torch head. Torch heads which are moderate to high powered require water cooling and it becomes difficult to design traditional concentric tube designed torch heads into a small package. Typically, the inner diameter of a torch head is about 0.25 in. This is a typical size for a spring wire liner which receives an electrode. When water passages are concentrically arranged about the inner diameter passageway, these passageways have a wall thickness of about 0.02 in. and a 0.05 in. gap to allow water to pass there through. Two water passageways are required to be used since one passageway allows the water to flow into the torch head while the other water passageway allows the water to return. When the size of these diameters are summed up, a concentrically designed welding torch head which only includes a passageway for the electrode and two water cooling passageways has a diameter of about 0.57 in. This diameter is based upon the ideal situation that desired size tubes are readily available and that thinly designed tubes have a large diameter but thin wall thicknesses are available. If these two ideal situations do not exist, the diameter of the welding torch body further increases. When one or more shielding gases are to be used, additional concentric passageways are required which results in an increased torch head diameter to accommodate these concentrically designed passageways for the shielding gas. The radial tube design of the torch head overcomes this problem by eliminating the required concentric passageways in typical torch heads and by providing the passageways for the one or more shielding gases and/or cooling fluids in the tubes themselves. Three or more small tubes are arranged in a generally circular pattern which diameter of the generally circular pattern is significantly less than the diameter of a concentrically designed welding torch head. By using the small tubes, it is possible to have thinner wall thicknesses and still maintain the structural rigidity of the welding torch head. In one specific aspect of this embodiment, radial tubes have an outer diameter of about 0.05-0.12 inch and a wall thickness of about 0.01-0.05 inch. The radial tube arrangement having ten tubes with a wall thickness of 0.02 inch and an inner passageway diameter of 0.05 inch that encircles a typical 0.25 inch spring wire liner forms a torch head diameter of about is 0.43 inch. The diameter is significantly less than traditional torch head diameters. In still another embodiment, two or more of the radial rods have the same outer diameter. In one specific aspect of this embodiment, all the radial rods have the same outer dimension.
In accordance with another aspect of the present invention, at least three radial rods form the body of the torch head. At least one of the radial rods includes an inner passageway to convey a shielding gas and/or cooling fluid. In one embodiment, the torch head body includes 3-20 rods, preferably 3-12 rods, and more preferably, 6-12 rods. In another embodiment, the torch head body includes at least one radial rod to convey a shielding gas and at least two radial rods to convey a shielding gas and at least two radial rods to convey a cooling fluid. In one specific aspect of this embodiment, the torch head body includes 1-10 radial rods for conveying one or more shielding gasses and 2-16 rods for conveying one or more cooling fluids. In yet another embodiment, the torch head body includes one or more structural rods. The structural rods provide structural rigidity and strength to the body of the torch head. The structural rods can be solid or include one or more non-solid sections. In one specific aspect of this embodiment, the torch head body includes 1-15 structural rods. In still another embodiment, one or more of the radial rods are made of metal. In one specific aspect of this embodiment, the radial rods include copper, copper alloy, stainless steel and/or titanium. In another specific aspect of this embodiment, two or more of the radial rods are made of the same material. In still another specific aspect of this embodiment, the shielding gas rods are made of the same material, the cooling fluid rods are made of the same material, the cooling fluid rods are made of the same material, and the structural rods are made of the same material.
In accordance with still another aspect of the present invention, a tip section is connected to the radial tubes at the tube end opposite of the tube end connected to the base section. In one embodiment, the upper portion of the tip section includes one or more passageways that are designed to receive shielding gas and to convey the shielding gas to the lower portion of the tip section. In another specific aspect of this embodiment, the upper portion of the tip section includes at least one passageway to fluidly connect two or more cooling tubes together. In another embodiment, the tip section includes a lower portion that has one or more passageways to convey a shielding gas about an electrode and/or weld pool during the welding process. In yet another embodiment, the tip section includes at least one electrode contact to form an electrical connection with an electrode. In one aspect of this embodiment, the tip section includes an electrical contact which is designed to engage a portion of the electrode in the tip section to form an arc between the electrode and the workpiece and/or to melt a portion of a consumable electrode to form the weld bead in the workpiece. In still another embodiment, the tip section includes at least one sleeve to direct a shielding gas about the electrode and on to the weld metal in the workpiece. In one aspect of this embodiment, two shielding gases are supplied to the torch head and the tip section includes two sleeves which are positioned adjacent one another such that the inner sleeve directs shielding gas around the electrode and weld metal and the outer sleeve directs a shielding gas about the shielding gas to form a stratified shielding gas about the electrode and weld bead. In accordance with yet another embodiment, the tip section includes an upper portion and a lower portion wherein the lower portion is releasably secured to the upper portion. The two-section design of the tip section enables an operator to remove the lower portion of the tip section for purposes of cleaning and inspection of the various components of the tip section without having to completely disengage the tip section from the radial rods. This design facilitates in easier cleaning and maintenance of the tip section.
In accordance with yet another aspect of the present invention, one or more of the radial tubes are coupled together between the ends of the radial tubes. In one embodiment, the coupler is in the form of solder wherein the solder connects together one or more of the radial rods. In another embodiment, the coupler is a coupling sleeve wherein two or more rods pass through the coupling sleeve and are rigidly held in position relative to one another by the coupling sleeve. In still another embodiment, the coupler engages all the radial rods to maintain them in position with respect to one another. In still another embodiment, two or more couplers can be used. In one specific aspect of this embodiment, a coupling sleeve in combination with solder is used to secure together the radial rods. As can be appreciated, other coupler arrangements can also be used individually or in combination to rigidly maintain two or more rods in location with respect to one another and/or to provide structural rigidity to the torch head.
In accordance with still yet another aspect of the present invention, two or more shielding gases are directed to the base section of the torch head and through a plurality of radial rods or tubes to provide a plurality of shielding gases about the electrode and/or weld bead. In one embodiment, an inert gas and carbon dioxide are directed to the weld pool region. The inert gas may be any number of gases such as argon, helium or the like. In another embodiment, the shielding gases are directed to the weld bead in a certain arrangement to create a stratified shielding gas about the electrode and/or weld rods. In one specific aspect of this embodiment, the inert gas is directed close to the electrode and the carbon dioxide is directed about the inert shielding gas. This stratified shielding gas arrangement has been found to make the bead hotter during welding and also to form a flatter weld bead which is highly desirable in various welding applications. The inert gas is used to prevent contamination of the weld metal during welding. The carbon dioxide, which surrounds the inert gas, increases plate heating and increases the effective heat about the electrode. Inert gas, such as argon and/or helium, by itself forms a cold weld which results in poor weld beads. Carbon dioxide by itself forms a hot weld which results in high spattering. The combination of these two gas during welding compliment one another to create a desirable welding environment. The increase in the effective heat enhances both the MIG welding process and the TIG welding process. The stratified gas welding increases the effective heat about the electrode, thus reducing spattering during welding. Another advantage of stratified gas welding is that reduced gas flows are required during welding thereby resulting in reduced costs. In still another embodiment, the ratio of the inert gas to the carbon dioxide is from about 1:1 to 1:10. In still yet another embodiment, the carbon dioxide volume through the torch head is greater than the inert gas volume. In a further embodiment, the shielding gases are directed in a laminar flow about the electrode and/or about the weld bead region during welding.
In still yet another aspect of the present invention, the welder includes a shielding gas controller to regulate the flow rate of shielding gas through the torch head so as to ensure the desired amount of shielding gas around the electrode and weld metal. When two or more shielding gases are used, the gas controller controls the flow rates and ratios of the shielding gases to the work place region. In one embodiment, the gas controller ensures that a substantially laminar flow of the one or more shielding gas is obtained through the tip section thereby providing controlled shielding about the electrode and/or in the weld area.
In still a further aspect of the present invention, the tip section of the torch head includes a wear resistance electrical contact. Many welding processes, which include the use of a consumable electrode, direct the consumable electrode through the tip section of the torch head. An electrical contact is positioned in the tip section to form an electrical connection with the moving consumable electrode. Generally, the electrical contact is copper. As the electrode passes through the tip section, the electrode wears down the electrical contact. As a result, faulty electrical connections between the consumable electrode and the tip section periodically occur, thus requiring a new electrical contact to be inserted into the tip section. In order the reduce or effectively eliminate the need to replace the electric contract over the life of the tip section, an improved electrical contact is provided in the interior of the tip section which electrical contact is wear resistance and provides satisfactory electrical conduction to the consumable electrode. In one embodiment, the electrical contact includes tungsten, a copper-tungsten alloy and/or a copper-ceramic matrix. Electrical contracts that include or are completely made of tungsten, a copper-tungsten alloy and/or a copper-ceramic matrix have excellent wear resistance. In one specific aspect of this embodiment, the electrical contract is made of tungsten. In another embodiment, the electrical contact is made of two of more components. In one specific aspect of this embodiment, the electrical contact includes an outer sleeve material that includes a material having a high thermal conductivity to increase the heat transfer from the outer sleeve to an interior sleeve. High thermal conductive materials include copper, copper alloys, aluminum and aluminum alloys. In another specific aspect of this embodiment, the electrical contact includes an inner sleeve having excellent wear resistant characteristics. Wear resistant materials include tungsten, a copper-tungsten alloy and/or a copper-ceramic matrix materials. In still another specific aspect of this embodiment, the outer sleeve is made of a different material from the inner sleeve. In still yet another specific aspect of this embodiment, the inner sleeve is removable from the outer sleeve. The ability to remove the inner sleeve enable the inner sleeve to be replaced when required without having to completely remove the electrical contact from the tip section of the torch.
In still yet a further aspect of the present invention, the tip section includes one or more fluid slots to direct a shielding and/or cooling fluid toward the end of the tip and/or onto the workpiece. The insertion of one or more slots in the tip insert causing the shielding gas to pass closer to the electrode passing through the tip insert. The closer passing gas provides additional cooling to the tip insert especially at the end of the tip insert. The slot configuration in the tip insert can also be arranged so as to minimize turbulent flow of the one or more shielding gasses and/or reduce the amount of turbulence about the end of the tip insert. Turbulence of the one or more shielding can interfere with the proper shielding of the workpiece and can also interfere with the stratification of the gasses when two or more shielding gasses are used. In one embodiment, the tip section includes a tip insert that can be a standard insert or a custom wear resistant insert as discussed above. In another embodiment, the one or more slots are located along the outer surface of the tip insert. In one aspect of this embodiment, the tip insert includes at least two slots. In another aspect of this embodiment, the tip insert includes at least three slots. In yet another aspect of this embodiment, the tip insert includes at least four slots. In still another aspect of this embodiment, the slots are symmetrically positioned about the tip insert. In still yet another aspect of this embodiment, the slots are non-symmetrically positioned about the tip insert. In yet another embodiment, one or more slots are positioned partially or fully along the length of the tip section. In still another embodiment, one or more slots form a linear or non-linear path along the longitudinal length of the tip insert. In still yet another embodiment, one or more slots a have a uniform or nonuniform width and/or depth along the longitudinal length of the tip insert. In one aspect of this embodiment, the width of the slots is uniform along the length of the tip insert. In another aspect of this embodiment, the depth of the slots is uniform along the length of the tip insert. In yet another aspect of this embodiment, the depth of the slots is uniform along a portion of the length of the tip insert and the depth varies along a different portion of the tip insert. In still another aspect of this embodiment, the depth of the slots varies along length of the tip insert. In one arrangement of this aspect, the depth of the slots is greater at the end of the tip insert than at the beginning of the tip insert.
It is a principal object of the present invention to provide an improved torch head which can be used in a variety of welding applications.
It is another object of the present invention to provide a torch head having a smaller diameter than standard torch heads.
It is still another object of the present invention to provide a welding torch which includes a plurality of radial rods forming a inner chamber of the welding torch.
It is still yet another object of the present invention to provide a welding torch which includes one or more radial welding rods having passages for the conveyance of shielding gas and/or a cooling fluid there through.
It is a further object of the present invention to provide a welding torch which includes one or more structural radial rods to provide rigidity to the torch head.
It is another object of the present invention to provide a welding torch which includes a coupler to connect one or more radial rods together to rigidify and/or provide structural integrity to the torch head.
It is still another object of the present invention to provide a welding torch that can provide stratified gas welding to the electrode and/or weld metal.
It is still yet another object of the present invention to provide a welding torch that can be used in MIG, MAG, plasma arc, STT, or TIG welding.
It is a further object of the present invention to provide a torch head which has a smaller diameter than standard welders and which incorporates a cooling fluid to cool a torch head during welding and which directs one or more shielding gases to the weld area to protect the electrode and/or weld metal during welding.
It is yet a further object of the present invention to provide a torch head which can be used with a consumable or non-consumable electrode.
It is still a further object of the present invention to provide a torch head which directs a shielding gas at a laminar flow about the electrode and/or weld area.
It is another object of the present invention to provide a welder which controls the amount and rate of shielding gas that is directed through the welding torch.
It is still another object of the present invention to provide a welding torch which controls the amount of cooling fluid which is directed through the welding torch.
It is still yet another object of the present invention to provide a welding torch which includes a welding tip that can be easily cleaned.
It is a further object of the present invention to provide a welding torch that has a welding tip that can be easily disconnected into a plurality of components to facilitate in easy and convenient cleaning and servicing.
It is yet a further object of the present invention to provide a welding torch that has a welding tip which includes a wear resistant electrical contact.
It is still a further object of the present invention to provide a welding torch which produces a weld bead and reduces the amount of spatter formed during the welding process.
I is another object of the present invention to provide a welding torch that includes a tip insert having one or more slots to direct a shielding and/or cooling fluid toward the end of the tip and/or onto the workpiece.
These and other objects of the present invention become apparent to one skilled in the art upon reading the description of the invention taken together with the accompanied drawings.